There's perhaps no actor in American movies today more amorphously casted and yet universally unrecognized as Peter Sarsgaard. In the past three years, we've seen him as a top-tier magazine editor, a live-at-home 26-year-old who digs graves for a sort-of living, a nondescript Southern lawyer, a deeply conflicted Gulf War subject - the list goes on and will continue. Here is an actor with an almost audacious interest in testing his boundaries as a performer, content playing characters of brazenly different social circumstances almost beyond the point of recognition.

Of course, the best character actors can make a career out of dodging the spotlight, as they not only lack a consistent appeal but also become a kind of omnipresent background figure ingrained in Hollywood culture. They're the "oh yeah, that guy" sort, the heir Steve Buscemi, who can dominate every other scene in a movie and yet escape the audience the moment they leave the theater.

Consider Sarsgaard's role in "Flightplan," German director Robert Schweitzer's tautly calculated thriller new on DVD, in which he plays an air marshal who subtly becomes the most dynamic figure in the movie. His role seems relatively boilerplate in the opening scenes: At first glance, he's the skeptical but goodhearted authority figure assigned to help the big-name lead (Jodie Foster) find her young daughter, who has gone missing. The movie's gimmick, of course, is that the daughter has disappeared on a commercial jet in mid-flight. The apparently constricting premise quickly leads to a host of stock possibilities: Where could she have gone in such a small space? Was she ever even on the plane in the first place?

Foster, exuding her usual confidence, naturally dominates the film's PR (the DVD artwork consists solely a frantic-looking snapshot of her), and her presence alone was no doubt responsible for much of the film's surprise success last fall. Meanwhile, Sarsgaard works in the commercial shadows, passing unnoticed in the movie's most complex and perplexing role.

The film itself plays heavily on post-Sept. 11 anxieties to mixed but always provocative effect, most saliently popping up in subplot confrontations between a Caucasian and Arab passenger. There are questions of terrorism elsewhere, too, but the movie neatly steps over them with its final revelation, which leads to an inescapably Hitchcockian final sequence that's as cleverly played as it is squarely in line with genre convention.

The actors' playfully dark performances help the film maintain its intensely and unwaveringly menacing atmosphere. Yes, its logic is easily penetrable, but overlook the obvious plot contrivances and you'll find a mood-drenched tease of a thriller that functions with reasonable flair on both an emotional and aesthetic level.

The film, like others in its vein, will endure on DVD as a stripped-down whodunit with a hint - and just a hint - of structural novelty. That said, the disc's features are decidedly routine: We get two basic, behind-the-scenes docs (which, to their credit, play less like the typical extended trailer and actually delve into the creative process) and an oft-awkward commentary track by Schweitzer. But this is a small blow to a movie among an increasingly rare breed of popcorn thrillers: conceptually high-minded and totally entertaining.

Film: 3 out of 5 stars
Special Features: 2.5 out of 5 stars